8250_em.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Renesas Emma Mobile 8250 driver
  4 *
  5 *  Copyright (C) 2012 Magnus Damm
  6 */
  7
  8#include <linux/device.h>
  9#include <linux/io.h>
 10#include <linux/module.h>
 11#include <linux/mod_devicetable.h>
 12#include <linux/serial_8250.h>
 13#include <linux/serial_reg.h>
 14#include <linux/platform_device.h>
 15#include <linux/clk.h>
 16
 17#include "8250.h"
 18
 19#define UART_DLL_EM 9
 20#define UART_DLM_EM 10
 21#define UART_HCR0_EM 11
 22
 23/*
 24 * A high value for UART_FCR_EM avoids overlapping with existing UART_*
 25 * register defines. UART_FCR_EM_HW is the real HW register offset.
 26 */
 27#define UART_FCR_EM 0x10003
 28#define UART_FCR_EM_HW 3
 29
 30#define UART_HCR0_EM_SW_RESET	BIT(7) /* SW Reset */
 31
 32struct serial8250_em_priv {
 33	int line;
 34};
 35
 36static void serial8250_em_serial_out_helper(struct uart_port *p, int offset,
 37					    int value)
 38{
 39	switch (offset) {
 40	case UART_TX: /* TX @ 0x00 */
 41		writeb(value, p->membase);
 42		break;
 43	case UART_LCR: /* LCR @ 0x10 (+1) */
 44	case UART_MCR: /* MCR @ 0x14 (+1) */
 45	case UART_SCR: /* SCR @ 0x20 (+1) */
 46		writel(value, p->membase + ((offset + 1) << 2));
 47		break;
 48	case UART_FCR_EM:
 49		writel(value, p->membase + (UART_FCR_EM_HW << 2));
 50		break;
 51	case UART_IER: /* IER @ 0x04 */
 52		value &= 0x0f; /* only 4 valid bits - not Xscale */
 53		fallthrough;
 54	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 55	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 56	case UART_HCR0_EM: /* HCR0 @ 0x2c */
 57		writel(value, p->membase + (offset << 2));
 58		break;
 59	}
 60}
 61
 62static u32 serial8250_em_serial_in(struct uart_port *p, unsigned int offset)
 63{
 64	switch (offset) {
 65	case UART_RX: /* RX @ 0x00 */
 66		return readb(p->membase);
 67	case UART_LCR: /* LCR @ 0x10 (+1) */
 68	case UART_MCR: /* MCR @ 0x14 (+1) */
 69	case UART_LSR: /* LSR @ 0x18 (+1) */
 70	case UART_MSR: /* MSR @ 0x1c (+1) */
 71	case UART_SCR: /* SCR @ 0x20 (+1) */
 72		return readl(p->membase + ((offset + 1) << 2));
 73	case UART_FCR_EM:
 74		return readl(p->membase + (UART_FCR_EM_HW << 2));
 75	case UART_IER: /* IER @ 0x04 */
 76	case UART_IIR: /* IIR @ 0x08 */
 77	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 78	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 79	case UART_HCR0_EM: /* HCR0 @ 0x2c */
 80		return readl(p->membase + (offset << 2));
 81	}
 82	return 0;
 83}
 84
 85static void serial8250_em_reg_update(struct uart_port *p, int off, int value)
 86{
 87	unsigned int ier, fcr, lcr, mcr, hcr0;
 88
 89	ier = serial8250_em_serial_in(p, UART_IER);
 90	fcr = serial8250_em_serial_in(p, UART_FCR_EM);
 91	lcr = serial8250_em_serial_in(p, UART_LCR);
 92	mcr = serial8250_em_serial_in(p, UART_MCR);
 93	hcr0 = serial8250_em_serial_in(p, UART_HCR0_EM);
 94
 95	serial8250_em_serial_out_helper(p, UART_FCR_EM, fcr |
 96							UART_FCR_CLEAR_RCVR |
 97							UART_FCR_CLEAR_XMIT);
 98	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0 |
 99							 UART_HCR0_EM_SW_RESET);
100	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0 &
101							 ~UART_HCR0_EM_SW_RESET);
102
103	switch (off) {
104	case UART_FCR_EM:
105		fcr = value;
106		break;
107	case UART_LCR:
108		lcr = value;
109		break;
110	case UART_MCR:
111		mcr = value;
112		break;
113	}
114
115	serial8250_em_serial_out_helper(p, UART_IER, ier);
116	serial8250_em_serial_out_helper(p, UART_FCR_EM, fcr);
117	serial8250_em_serial_out_helper(p, UART_MCR, mcr);
118	serial8250_em_serial_out_helper(p, UART_LCR, lcr);
119	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0);
120}
121
122static void serial8250_em_serial_out(struct uart_port *p, unsigned int offset, u32 value)
123{
124	switch (offset) {
125	case UART_TX:
126	case UART_SCR:
127	case UART_IER:
128	case UART_DLL_EM:
129	case UART_DLM_EM:
130		serial8250_em_serial_out_helper(p, offset, value);
131		break;
132	case UART_FCR:
133		serial8250_em_reg_update(p, UART_FCR_EM, value);
134		break;
135	case UART_LCR:
136	case UART_MCR:
137		serial8250_em_reg_update(p, offset, value);
138		break;
139	}
140}
141
142static u32 serial8250_em_serial_dl_read(struct uart_8250_port *up)
143{
144	return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
145}
146
147static void serial8250_em_serial_dl_write(struct uart_8250_port *up, u32 value)
148{
149	serial_out(up, UART_DLL_EM, value & 0xff);
150	serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
151}
152
153static int serial8250_em_probe(struct platform_device *pdev)
154{
155	struct serial8250_em_priv *priv;
156	struct device *dev = &pdev->dev;
157	struct uart_8250_port up;
158	struct resource *regs;
159	struct clk *sclk;
160	int irq, ret;
161
162	irq = platform_get_irq(pdev, 0);
163	if (irq < 0)
164		return irq;
165
166	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
167	if (!regs)
168		return dev_err_probe(dev, -EINVAL, "missing registers\n");
169
170	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
171	if (!priv)
172		return -ENOMEM;
173
174	sclk = devm_clk_get_enabled(dev, "sclk");
175	if (IS_ERR(sclk))
176		return dev_err_probe(dev, PTR_ERR(sclk), "unable to get clock\n");
177
178	memset(&up, 0, sizeof(up));
179	up.port.mapbase = regs->start;
180	up.port.irq = irq;
181	up.port.type = PORT_16750;
182	up.port.flags = UPF_FIXED_PORT | UPF_IOREMAP | UPF_FIXED_TYPE;
183	up.port.dev = dev;
184	up.port.private_data = priv;
185
186	up.port.uartclk = clk_get_rate(sclk);
187
188	up.port.iotype = UPIO_MEM32;
189	up.port.serial_in = serial8250_em_serial_in;
190	up.port.serial_out = serial8250_em_serial_out;
191	up.dl_read = serial8250_em_serial_dl_read;
192	up.dl_write = serial8250_em_serial_dl_write;
193
194	ret = serial8250_register_8250_port(&up);
195	if (ret < 0)
196		return dev_err_probe(dev, ret, "unable to register 8250 port\n");
197
198	priv->line = ret;
199	platform_set_drvdata(pdev, priv);
200	return 0;
201}
202
203static void serial8250_em_remove(struct platform_device *pdev)
204{
205	struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
206
207	serial8250_unregister_port(priv->line);
208}
209
210static const struct of_device_id serial8250_em_dt_ids[] = {
211	{ .compatible = "renesas,em-uart", },
212	{},
213};
214MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
215
216static struct platform_driver serial8250_em_platform_driver = {
217	.driver = {
218		.name		= "serial8250-em",
219		.of_match_table = serial8250_em_dt_ids,
220	},
221	.probe			= serial8250_em_probe,
222	.remove			= serial8250_em_remove,
223};
224
225module_platform_driver(serial8250_em_platform_driver);
226
227MODULE_AUTHOR("Magnus Damm");
228MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
229MODULE_LICENSE("GPL v2");